Problem: Solve for $x$ : $-6 = x - 20$
Explanation: Add $20$ to both sides: $ \begin{eqnarray} \\ \hphantom{-6 {+ 20}} &\hphantom{=}& \hphantom{x} \\ -6 &=& x - 20 \\ \\ {+20} && {+20} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -6 {+ 20} &=& x \\ \end{eqnarray} $ Simplify. $ x = 14$